Volkswagen's 2015 diesel emissions scandal isn't entirely in its rearview mirror yet, and now another scandal threatens the automaker. VW confirmed this week that it sold thousands of pre-production Volkswagen vehicles as used cars, which did not meet regulations in the United States and Europe.

German publication Handelsblatt reported on VW's admission after a spokesperson told reporters 6,400 pre-production cars were sold between 2006 and 2018. To make matters worse, Herbert Diess, CEO of VW Group, was aware of the practice since 2016 when he headed the Volkswagen brand. It took the automaker two years to finally inform owners their cars were sold without proper licensing from regulatory bodies. VW did not sell pre-production cars from other brands—only its mass-market Volkswagen brand.

Pre-production cars are often very close to final production vehicles, but can sometimes have differences. The cars may not be certified for sale and often face a date with the crusher after their intended purposes for media events and tests. Instead, VW sold the cars as used cars, which meant U.S. and European regulators never gave the green light for their sale. 

The few thousand cars is a drop in the bucket compared to millions vehicles that emitted far greater emissions due to "defeat devices," but the latest hiccup at VW may speak to a larger carelessness. An unnamed industry official called it "a gigantic mistake" for VW to have passed along pre-production vehicles to consumers.

VW's official recall for the pre-production cars varies. Some of them only need software updates or a revised navigation system. Others are so far out of spec from production series models that VW will finally scrap them. The German automaker said the cars could have been sold legally if VW documented their differences with the proper authorities, but it failed to do so for more than 10 years.

It's unclear how the U.S. plans to proceed after identifying the scandal, but German authorities are now weighing their options. VW could face fines for every pre-production vehicle it sold over the 12-year period. The automaker could also face numerous lawsuits from owners who purchased cars that did not meet the automaker's marketed criteria.